Annular mask contact lenses

ABSTRACT

An annular mask contact lens designed to operate with the normal functioning of the human pupil. An annular mask forms a small pinhole-like aperture on the contact lens enabling continual focus correction. The outer diameter of the annular mask allows the wearer to transmit more light energy through the pupil as brightness levels decrease. The contact lens may be structured with two separate and distinct optical corrections, both at the small aperture region and in the region beyond the annular mask. Functional imaging is thus achieved for both bright and dim lighting, and over a wide range of viewing distances. Cosmetic and peripheral vision enhancement is also provided by the contact lens constructed according to the invention.

REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.08/120,970 filed on Sep. 13, 1993 which, in turn, is acontinuation-in-part of U.S. application Ser. No. 07/791,121, filed Nov.12, 1991 now U.S. Pat. No. 5,245,367.

BACKGROUND OF THE INVENTION

This invention concerns a contact lens for vision correction and, inparticular, annular mask contact lenses and related methodology.

Contact lenses are commonplace today. Most individuals with averagerefractive errors can quickly and easily acquire and use these lenses inplace of prescription eye glasses. This is not true, however, forindividuals who are presbyopic, i.e., those requiring multi-focal visualcorrection, or for those individuals with structural eye abnormalities.These individuals are left with little choice in selecting comfortable,effective contact lenses. Lenses which are available typically encumberthese wearers with other difficulties, and are usually very expensive.Presbyopic individuals, for example, who choose to wear soft contactlenses are usually fitted in a "monovision" mode, where one eye iscorrected for near vision, and the other eye is corrected for farvision. Further, the commercially available soft multifocal contactlenses are effective only for early presbyops, and are difficult to fitand to produce consistently.

The long felt need to develop more versatile multifocal lenses has leddesigners to pinhole contact lenses. These lenses endeavor to utilizethe known theories of pinhole imaging, commonly understood in optics asa method to reduce geometrical aberrations, e.g., astigmatism, sphericalaberration, and coma. By restricting a person's vision to a small"pinhole" aperture, visual deficiencies can be reduced or effectivelyremoved. Unfortunately, the utility of this technology has been dilutedbecause of designs and approaches inappropriate for effective correctiverefractive prescriptions. For upwards of 50 years, pinhole contactlenses have been under consideration, yet they remain today commerciallyunsuccessful and largely unavailable. As a result, wearers afflictedwith relatively poor vision are typically unaided by contact lenses.

"Multiple Focal Contact Lenses", as described in U.S. Pat. No.3,794,414, was one attempt to develop small-aperture contact lenses.This approach combined a pinhole-like aperture with radial slits andscalloped masking regions on a contact lens supposedly to correct bothperipheral vision and the effects related to decentered contact lenses.The contact lenses were made from a rigid substrate, and "floated" onthe eye, creating a need for apertures over a large portion of the lens.The disclosed designs through, i.e., the use of scalloped patterns andradial slits, actually encourage diffraction effects at the retina. Thisreduces image quality. The nature of small-aperture correction is tocorrect geometrical aberrations in excess of diffraction. Therefore, thebenefits achieved according to that patent by incorporating the small,pinhole-like, aperture, are likely to be offset by undesirablediffraction effects.

In addition, the teachings in the aforementioned patent do not generallyconsider the normal functioning of the human pupil. One significantdrawback in pinhole imaging is energy starvation. Small-aperture lensesimprove image quality, but at the same time block significant amounts oflight energy from reaching the retina. Under dim lighting conditions, ahuman pupil normally dilates. Without proper consideration, asmall-aperture contact would equivalently place a person into darkness,even though the lighting is only dim or low.

Pinhole correction together with the normal functioning of the humanpupil is considered in U.S. Pat. No. 4,955,904, which presents anintraocular lens surgically implanted within the eye. The patent,entitled "Masked Intraocular Lens and Method for Treating a Wearer WithCataracts", affords cataract wearers some form of vision correctionthrough surgery. The intraocular lens is masked to form a pinhole thataccommodates the function of the human pupil under different lightingconditions. But, intraocular lenses have operational and otherdrawbacks. They are not contact lenses; surgery is required and the lensmust be permanently implanted with precision, typically through the useof man-made loops. Furthermore, because of material requirements forimplantation, these impenetrable lenses can transmit little or nooxygen, a feature widely available in contact lenses. Contact lenses, inaddition, are conveniently installed and removed by the wearer, and areheld in place on the eye through tear and lid tension.

With this background, an object of this invention is to provide animproved small-aperture contact lens, and in particular, one whichaccommodates the normal function of the human pupil.

Another object of this invention is to present a contact lens whichprovides functional imaging during both bright and dim lightingconditions, and over a wide range of viewing distances.

Yet another object of this invention is to provide a small-aperturecontact lens and related methodology to reduce the appearance of pinholecontact lenses on the eye of the wearer.

Other objects of the invention are evident in the description thatfollows.

SUMMARY OF THE INVENTION

The present invention provides, in one aspect, improvements to a contactlens that has a transparent lens body. The lens body has a first surfaceconfigured, for the most part, to conform to the eye curvature of thewearer. A second surface, opposite to the first surface, is opticallyconfigured, in relation to the first surface, to correct the vision ofthe wearer for a focus between near and far objects. The lens body has amask that forms an annulus pattern with a small, so-called pinholeaperture. The annular mask is arranged to accommodate the pupil of thewearer over different viewing distances and differing brightness levels.Thus, during average light conditions, the annular mask reduces thelight energy through the pupil of the wearer; and in dimmer lightconditions, the annular mask permits relatively more light energy topass through dilated pupil of the wearer to reach the retina. In apreferred aspect, the annular mask is sized such that, during dimlighting conditions, the wearer's dilated pupil is larger than thedenser section of the annular mask and substantially unrestricted lightenergy passes outside the annular mask region and through the wearer'spupil.

In another aspect according to the invention, the second surface of thecontact lens has an optical configuration outside the annular maskregion which corrects the vision of the wearer selectively at a focusbetween and including near and far objects. Thus, the second surfaceforms a multipowered surface: within the annular mask, the secondsurface corrects the wearer's vision selectively at a first distance;and outside the annular mask, the second surface corrects the wearer'svision selectively at a second distance. Preferably, the first distanceis an intermediate one, between near and far objects; and the seconddistance is at far objects.

In other aspects, the first and/or second surface of a contact lensconstructed according to the invention includes an optical correction.For example, the first and/or second surfaces has an aspheric, concave,or toric form to correct certain deficiencies in the vision of thewearer. The second surface can additionally have a convex form as anoptical correction.

In yet other aspects according to the invention, the lens body is madewith oxygen permeable material, or with flexible polymer material toform a rigid or soft contact lens.

A contact lens constructed in accordance with the invention has furtheraspects relating to physical dimensions. For example, in one aspect, thelens body has an outer diameter of between approximately seven andeighteen millimeters. In another aspect, the pinhole aperture has adiameter of between approximately one-half and three millimeters. Inanother aspect, the annular mask region forms an annulus with a radialwidth of between approximately one-half and four millimeters.Preferably, however, the annular mask region has a total diameter ofapproximately four and one-half millimeters.

In yet another aspect, a contact lens constructed according to theinvention has a lens body which is selectively colored or tinted. Thiscoloring can be employed for cosmetic reasons, as well as to improve thefunction of the annular mask.

The annular mask region is selectively patterned, colored or tinted, inanother aspect, to further reduce the appearance of the annular maskregion when viewed on the wearer. For example, one patterned annularmask according to the invention is feathered along its outercircumference or border, such that the edge contrast of the annular maskis degraded. In a preferred aspect, the annular mask region isselectively colored or tinted to match, enhance, or otherwise change theappearance of the iris color of the wearer. This too can be for cosmeticreasons; and additionally it can reduce or modify the appearance of theannulus when viewed on the wearer's eye.

In still another aspect, a contact lens constructed according to theinvention has an annular mask with an optical transmissivity in thevisible electromagnetic spectrum between approximately zero and ninetypercent. In one preferred aspect, the chosen transmissivity is achievedthrough a plurality of light-blocking dots, arranged for selectivelyreducing the transmission of light energy through the annular maskregion by between approximately ten and one hundred percent. In anotheraspect, the annular mask region is selectively translucent, therebyreducing and diffusing light to the wearer's pupil. In most practicalapplications, the amount of transmissivity through the annular mask isrelatively small, typically less than twenty percent.

A contact lens constructed in accordance with the invention ispreferably shaped or weighted to restrict the motion of the lens bodyrelative to the eye of the wearer to less than approximately one andone-half millimeter. For example, and in one aspect, a prism ballastweight with the lens body reduces unwanted motion of the lens on theeye. In still another aspect, weighting or shaping of the lens bodycenters the pinhole aperture created by the annular mask at the optimalposition on the eye of the wearer.

In still another aspect in accordance with the invention, the annularmask region has at least one transmissive artifact that is free fromobscuration, such as the obscuration forming the selectivelytransmissive annular mask region. The transmissive artifact thusrepresents an area that transmits light energy through the lens bodywith a transmission similar to the transmission of light energy throughthe pinhole aperture. Preferably, the transmissive artifact has ageometrical optical arrangement that improves the peripheral vision ofthe wearer. The artifact has a shape and size which does not createunwanted diffraction effects. For example, one acceptable transmissiveartifact pattern is created by three slits arranged in 60° arcs aboutthe annulus.

The invention provides, in another aspect, methodology to manufacture acontact lens, including the steps of: (1) forming a contact lens bodywith a first surface configured to conform to the eye curvature of awearer and with a second surface configured to correct the vision of thewearer selectively at a focus between and including near and farobjects; and (2) providing an annular mask region of selected opticaltransmissivity with the lens body. According to this aspect, the annularmask region forms a substantially pinhole-like aperture which transmitslight energy through the pupil of the wearer. The annular mask regionfurther reduces light energy through the pupil of the wearer duringaverage lighting conditions, while permitting more light energy to passthrough the pupil of the wearer during lower lighting conditions as thepupil dilates.

In a preferred aspect, the method includes the further step of providingan optical correction outside the annular mask region to correct thevision of the wearer selectively at a focus between and including nearand far objects, thus forming a multi-powered second surface.

In yet other aspects, the method includes the step of providing anoptical correction, such as with an aspheric, toric, convex or concaveform, on the second surface of the lens body. Alternatively, oradditionally, the method includes the step of providing an opticalcorrection, such as with an aspheric, toric or concave form, on thefirst surface.

In yet other aspect, the method includes the further step of optimizingthe size of the annular mask region to fit the particular pupil size ofthe wearer. In still another aspect, additional mask is provided toselectively block portions of the wearer's pupil that contributeundesirable image effects, such as created by those portions of the eyethat are damaged or scarred.

A method according to the invention includes, in still other aspects,the step of weighting or shaping the lens body to maintain a particularorientation on the eye of the wearer. The lens body can also be weightedor shaped to center the aperture at the pupil of the wearer. In apreferred aspect, a method for manufacturing a contact lens inaccordance with the invention includes the step of configuring the lensbody, e.g., with a weight such as a prism ballast or with shaping of thelens body, such that the lens body is restricted for movement of lessthan approximately one and one-half millimeters relative to the eye ofthe wearer.

In other aspects, a method according to the invention includesalternative or additional steps for forming the annular mask region. Forexample, in one aspect the annular mask is formed by providinglight-blocking areas with or within the lens body that are arranged toreduce the transmission of light energy selectively through the annularmask region by between approximately ten and one hundred percent. In onepractice according to the invention, transmission through the annularmask is reduced by disrupting the refractive power of the lens in thearea of the annular mask by laser or chemical etching, or by physicalabrasives. In a related aspect, the annular mask is formed by providingvariably transmissive coatings with the lens body such that light energyis selectively transmitted through the annular mask region by betweenapproximately zero and ninety percent. Typically, however, thetransmission through the annular mask is less than twenty percent.Alternatively, and in another aspect, a light-restricting element isemployed within the lens body to form the annular mask region.

One aspect of the invention includes the step of forming lighttransmitting artifacts within the annular mask region. Thesetransmitting artifacts represent areas that transmit light energythrough the lens body with a transmission similar to that of theaperture. Accordingly, these transmitting artifacts are not opticallyopaque, but rather freely transmit light energy through the wearer'spupil, much like the aperture does. The transmitting artifacts arepreferably arranged in a geometrical optics configuration to improve theperipheral vision of the wearer. They are also arranged to reduceunwanted diffraction effects caused by the artifacts at the retina.

In a preferred aspect, a method according to the invention includes thefurther step of patterning, coloring, or tinting the annular mask regionto reduce the appearance of the annular mask when viewed on the eye ofthe wearer. Feathering techniques, for example, create acceptablepatterns which tend to reduce the annular mask appearance.

In still another aspect, the invention provides for a non-surgicalmethod for treating wearers with visual aberrations, including the stepsof: (1) fitting at least one eye of a wearer with a first contact lensconfigured to correct the vision of a wearer at a focus between andincluding near and far objects; and (2) providing an annular mask regionof selected optical transmissivity to the contact lens. In this method,the annular mask region is arranged to form a substantially pinhole-likeaperture for the pupil of the wearer. The annular mask regionsubstantially obscures the pupil of the wearer during average lightingconditions except for the small aperture, while permitting more lightenergy to pass through the pupil of the wearer during lower lightingconditions, such as when the pupil dilates.

A non-surgical method as described above can include the additionalsteps of (1) fitting only one eye of the wearer with the first contactlens and (2) fitting the other eye with a different contact lens, e.g.,one of selected power, and one that is substantially free of an annularmask region.

The advantages of a contact lens constructed in accordance with theinvention are several. The lens improves a wearer's vision over a widerange of viewing distances. The lens improves a wearer's vision duringdiffering brightness conditions by incorporating the normal function ofthe human pupil in the size of the annular mask. Moreover, complexvision correction is possible with the invention by providing amulti-powered contact lens. If a wearer has an area on the iris which isdamaged or surgically removed, these portions can be selectivelyblocked, according to the invention, for further vision improvement. Acontact lens according to the invention does not encourage diffractioneffects, thereby avoiding a reduction in visual acuity. A contact lensaccording to the invention also achieves an acceptable cosmeticappearance, unlike known pinhole contact lenses; in particular, with thelens of the invention, the annular mask has a reduced appearance whenviewed on the eye of the wearer.

These and other aspects and features of the invention will be more fullyunderstood in the detailed description which follows.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention,reference should be made to the following detailed description and theaccompanying drawings, in which:

FIG. 1 is a plan view of an annular mask contact lens constructed inaccordance with the invention;

FIG. 1A is a diametrical sectional view of the lens of FIG. 1;

FIG. 1B is a diametrical sectional view of the lens of FIG. 1 with aprism ballast;

FIG. 1C is a diametrical sectional view of the lens of FIG. 1 with aninternal light-blocking element forming the annular mask;

FIG. 2 illustrates an annular mask contact lens according to FIG. 1 andits relation to the human pupil during average light conditions;

FIG. 2A is a diametrical sectional view of the lens of FIG. 2;

FIG. 3 illustrates an annular mask contact lens constructed according tothe invention and its relation to the human pupil where the annulus issmaller than the wearer's dilated pupil under dim lighting conditions;

FIG. 3A is a diametrical sectional view of the lens of FIG. 3;

FIG. 4 shows the contact lens of FIG. 1 with a feathered annulus;

FIG. 5 shows the contact lens of FIG. 1 with light-transmittingartifacts;

FIG. 6 illustrates a bi-powered annular mask contact lens constructed inaccordance with further features of the invention; and

FIG. 7 illustrates an annular mask contact lens constructed inaccordance with further features of the invention and which selectivelyblocks portions of the human pupil.

DESCRIPTION OF ILLUSTRATED EMBODIMENTS

FIGS. 1 and 1A show a contact lens 10 constructed in accordance with theinvention: FIG. 1 shows the contact lens 10 in a front view; while FIG.1A shows the contact lens 10 in a side sectional view. The contact lens10 has a transparent lens body 12 that is manufactured by knowntechniques and methods in the art.

In accordance with the improvements of the invention, the lens body 12has a first surface 14 optically configured, e.g., with a concave form,to conform to the eye curvature of the wearer. The lens body 12 has asecond surface 16 optically configured, e.g., with a convex form, tocorrect the vision of the wearer selectively at a focus between andincluding far and near objects. Focusing is achieved both by the contactlens 10 and by the refractive capability of the wearer's eye.

The contact lens 10 has an annular mask 18 that is selectivelytransmissive according to the particular needs of the wearer. In apreferred embodiment, the annular mask 18 is opaque such that it blockslight energy at the lens body 12. The annular mask 18 is furtherarranged to form a substantially pinhole-like aperture 20 at thewearer's optical line-of-sight 22, which is approximately at the centerof the lens body 12. The aperture 20 is preferably arranged to beconcentric with the wearer's pupil, which could be off-center withrespect to the curvature of the cornea.

Constructed in this fashion, the contact lens 10 operates as a pinholeimager and increases the depth of focus for objects viewed by thewearer. Light rays from a single object in the field of view, andentering the pinhole aperture 20, are more tightly imaged at the retinathan in the absence of the lens 10. This reduces the blurring at theretinal image and increases the wearer's visual acuity. Normally, thetypical geometrical vision deficiencies encountered in wearers, likemyopia, hyperopia, astigmatism, and presbyopia, spread out the lightrays reaching the retina from a single object point in the field ofview, thereby reducing image contrast. The pinhole aperture 20 limitsthese light rays to a small bundle entering the eye pupil, and therebyimproves image contrast. Visual acuity is also improved over a largerange of viewing distances because defocus effects are less noticeablewith the reduced blurring of the image at the retina.

The pinhole aperture 20 is sized to provide pinhole imaging improvementfor the wearer's vision deficiency. The aperture 20 is smaller than thewearer's pupil size during average lighting conditions to improve visionclarity during such conditions. Preferably, however, the aperture 20 issmaller--or approximately equivalent to--the pupil of the wearer duringbright light conditions. With this latter sizing, the wearer hasimproved vision clarity even during bright lighting conditions.

Thus the aperture 20 is less than approximately four millimeters, toaccommodate the variety of pupil diameters under average lightingconditions. Since the contact lens may not always center over thewearer's pupil, the lens 10 is preferably fitted first, and the positionof the annulus 18 noted, and the lens 10 then made to special orderaccording to the fitting so the annulus 18 centers over the wearer'spupil. In a preferred embodiment, the lens body 12 is weighted, e.g.,with a prism ballast 17 in FIG. 1B, or shaped to center the aperture 20at the optimal location on the eye of the wearer, and to reduce themovement of the contact 10 on the wearer's eye, preferably to less thanapproximately one and one-half millimeters. Accordingly, the lens 10 isheld in a relatively constant position on the eye of the wearer, therebymaximizing the lens 10 for central vision while reducing the possibilityof a reduction in the peripheral field by decentering and otherexcessive movements.

At the same time, the pinhole aperture 20 desirably is greater than thediameter at which diffraction effects start to degrade image quality. Ingeneral, the benefits achieved by the pinhole aperture 20 can bedestroyed by diffraction if very small apertures are incorporated intothe pinhole contacts lenses. Such small apertures that have theseadverse results include radial slits and scalloped patterns. Diffractioncan actually increase the blurring of the retinal image such that thewearer's vision is degraded rather than improved. Thus, to avoidunacceptable diffraction effects, the lower limit of a pinhole aperturein a usable contact lens is approximately one-half millimeter.

Therefore, the diameter of the pinhole aperture 20 is generally greaterthan one-half millimeter and less than four millimeters. In a preferredembodiment, the pinhole aperture 20 is approximately two millimeters indiameter.

In addition, the radial width of the annular mask 18, from the insideedge 24 to the outside edge 26, is preferably between approximatelyone-half and four millimeters. This dimension is sized in the practiceof the invention to accommodate the normal function of the human pupil,as described below. Typically, the annular mask 18 has a diameter ofapproximately four and one-half millimeters.

The lens body 12 can be constructed with material to form a hard, gaspermeable lens, or, alternatively, to form a soft contact lens, e.g.,with a flexible soft polymer material. Combinations of these materialsare also suitable to form a composite contact. The outer diameter of thelens body 12 is approximately seven to eighteen millimeters, dependingupon the wearer's eye size.

It can be appreciated that the dimensions of the annular mask 18 can beadjusted for a particular wearer. For example, the annular mask 18 canbe sized for a particular pupil, or further optimized for a desiredvisual correction.

For ease of manufacture, the second surface 16 is appropriatelyconfigured and powered to correct the vision of the wearer for distantobjects. In a preferred embodiment, however, the second surface 16 isconfigured within the annular mask 18, i.e., at the pinhole aperture 20,to correct the wearer's vision at an intermediate focus, approximatelymidway between near and far objects. According to this embodiment, thelens 20 is multi-powered: the lens body 10 corrects the wearer's visionfor far objects outside the annular mask 18, and corrects forintermediate objects within the pinhole aperture area.

It should be apparent to those skilled in the art that othermultipowered corrections are possible without departing from the scopeof the invention.

The contact lens 10 typically corrects the wearer's vision by forming anoptical correction on the second surface 16. Common corrections includeconvex, concave, toric, and astigmatic forms. Alternatively, or inconjunction with the an optical correction on the second surface, thefirst surface can similarly include an optical correction, such as witha toric, astigmatic, or concave form.

FIGS. 2 and 2A illustrate the relationship of the annular mask contactlens 10 of FIGS. 1 and 1A to the wearer's contracted pupil 28 duringaverage conditions. Light rays 30 show the bundle of light from a farobject point which passes through the wearer's pupil 28 without thecontact lens 10. Light rays 32 show the smaller bundle of light from thesame object point which passes through the wearer's pupil with thecontact lens 10. Light rays 32 pass by the edge of the pinhole aperture20 and do not pass by the edge of the human pupil 28. The light rays 32are focused by the contact lens 10 and by the eye's refractive portions34.

Under normal viewing, without the contact lens 10, the wearer's retina36 would receive all the light energy from the light rays 30. The lightrays 30 would pass by the edge of the eye pupil 28 and eventually reachthe retina 36, where the light energy is converted into signalsperceived by the brain.

However, while viewing through the contact lens 10 under average light,or daylight, conditions, the pinhole aperture 20 created by the annularmask 18 restricts the effective light transmitting aperture so that onlythe light rays 32 pass through the eye pupil 28 and to the retina 36.Because the light rays 32 constitute a smaller geometrical extent uponthe eye's refractive portions 34, as compared to the light rays 30, theaberrations and/or defocussing effects at the retina 36 are reduced.

FIG. 2A shows that the functional size of the eye pupil 28 is opticallylarger than the effective diameter created by the pinhole aperture 20 ofthe contact lens 10 under average light conditions. The light raysentering the eye through the pinhole aperture 20 are restricted to asmaller geometrical extent, as compared to the light rays which wouldotherwise pass through the eye pupil 28. The smaller bundle of lightpassing through the pinhole aperture 20 is thus more tightly focused atthe retina, thereby improving the clarity of objects viewed by thewearer.

In contrast to FIGS. 2 and 2A, FIGS. 3 and 3A show one embodiment of acontact lens 11, similar to the contact lens 10 of FIGS. 1-2,constructed in accordance with the invention whereby the outer diameterof the annulus 19 is sized to accommodate a wearer's dilated pupil 28during lower light conditions. The bundle of light rays 38 from the sameobject point strikes the contact lens 11 in the regions 40, 42, and 44,and are focused at the retina 36 by the contact lens 11 and the eye'srefractive portions 34. The eye pupil 28 is illustratively shown as thewearer's limiting aperture under normal viewing without the contact lens11, where the wearer would receive light energy from all the light rays38. The light rays 38 would pass through the edge of the pupil 28 andeventually reach the retina 36. Because of the dimmer lighting, thewearer's pupil 28 has dilated from its size shown in FIGS. 2 and 2A toacquire more light energy at the retina 36. The widely dilated pupiloccurs most readily under dim illumination when a person's attention isprimarily drawn to distant objects.

The annular mask 19 of the contact lens 11 is sized to increase theavailable transmission through the pupil 28 and to the retina 32 underdimmer lighting, as compared to average light conditions shown in FIG.2. As seen in FIG. 3A, the pupil 28 is optically larger than theeffective diameter of the annular mask 19 after the wearer's pupildilates. During lower light conditions, the wearer can thus receivelight rays 38 at the retina 36 through the transmitting regions 40 and42. The energy passing through the region 40 is transmitted through thepinhole 21, and to the retina 36. The light energy passing through theregion 42 is transmitted outside the annular mask 19 and to the retina36. Some of the light rays 38 are blocked at the region 44 by theannular mask 19.

Accordingly, the contact lens 11 increasingly transmits more of thelight rays 38 as the wearer's pupil size increases or dilates. Thewearer is, therefore, better able to discern the same objects which wereviewed under brighter conditions.

Alternatively to, or in conjunction with, the contact lens 11illustrated in FIGS. 3 and 3A, the annular mask 18 (FIGS. 1-2) or 19(FIGS. 3-3A) is variably and selectively transmissive to provide morelight energy to the retina as the wearer's pupil dilates.

Whether in the form of a coating or other structure, the mask region 18(FIG. 1) and 19 (FIG. 3) can have various selected levels oftransmissivity. To take full advantage of the versatility in visioncorrection available in a pinhole contact lens according to theinvention, the annular mask region is variably transmissive through thelens body to between approximately zero and 90% in the visible lightspectrum. Opacity is generally desired for maximal visual sharpness.However, a person may want a to transmit more light energy through theannulus to avoid a sense of visual dimness, i.e. to attain morebrightness. Typically, an annulus transmission of less thanapproximately twenty percent is sufficient for this purpose. The opticaltransmissivity of a mask region according to the invention can thereforevary from lens to lens, as well as within a lens, to attain visionhaving a selected balance of factors. For example, in one practiceaccording to the invention, the annular mask transmits less light energytowards the pinhole aperture, and transmits relatively more light energytowards the outer edge of the contact.

Those skilled in the art will appreciate that the mask regions of thelenses 10 and 11 in FIGS. 1-3 can be constructed in several ways. Onepractice for achieving this transmissivity utilizes a light-blockingelement 37, shown in FIG. 1C, configured with the body to restrict lightpassage through the lens body. Another practice uses a variablytransmissive coating applied to, or manufactured with, the lens body.Yet another practice generates the annular mask with a plurality oflight-blocking dots, which in total reduce the transmission of lightenergy through the annulus to the selected transmissivity, for exampleby between approximately ten and one hundred percent. Typically,however, the light-blocking dots restrict over eighty percent of thelight energy transmitted through the annular mask.

Still other practices for forming the annular mask region include Diazocontact printing, mesoprints, and reactive and VAT dyes. Other practicesfor forming the annular mask include a variety of methods for disruptingthe surface or refractive properties of the lens in the area of theannular mask. For example, lasers or chemical etchants, or physicalabrasives, are effectively used to disrupt the optical surface of thecontact to change the transmission in the annular mask region to formthe annular mask. Suitable techniques for disrupting and creating suchoptical surfaces are described in U.S. Pat. No. 4,744,647, entitled"Semi-Opaque Corneal Contact Lens or Inraoccular Lens and Method ofFormation", which is accordingly incorporated herein by reference.

A particularly advantageous practice for achieving the variablytransmissive annular mask utilizes PAD FLEX, or Italio Platemethodology, which is well-known to those skilled in the art. In PADFLEX printing, for example, a silicone tip contacts an Italio plateengraved with a selectable pattern and covered with ink. The tipacquires the image from the Italio plate and then transfers the imagewithout distortion onto a wide range of curved surfaces, such as acontact lens.

Accordingly, a contact lens 10 (FIGS. 1-2) constructed with atransmissive annulus 18, rather than a light-blocking annulus, may besized with a diameter greater than the annulus 19 of FIG. 3. Since lightenergy is transmitted throughout the annulus 18, more light energy istransmitted through the pupil 28 as the pupil dilates. Therefore, thereis no requirement that the pupil 28 exceed the annulus diameter, such asillustrated in FIGS. 3-3A. However, the annulus 19 of FIGS. 3-3A isappropriately transmissive in some instances to further increase thelight energy to the retina.

The size of the annular masks 18 and 19, FIGS. 2 and 3, provides certainadvantages, particularly with respect to the pinhole aperture. Forexample, during eye examinations, a doctor can pharmacologically dilatethe pupil of a person wearing the contact lens, and examine the entireretina, up to the periphery. This generally cannot be done through anormal pupil that is approximately two millimeters or less in diameter.

A contact lens constructed in accordance with the invention, such as thelens 10 of FIGS. 1-2, is colored, tinted, or otherwise shaded, whenappropriate, by methods known in the art. This coloring or tinting canbe cosmetic, as it often is for many wearers of common contact lenses.It can also reduce the sometimes objectionable appearance of the annularmask 18 when viewed on the eye of the wearer. For example, the inventionprovides for an annulus that is matched to the wearer's iris. It alsoprovides for an annulus that enhances or changes the appearance of thewearer's iris, if desired.

In one preferred embodiment, the annular mask 18 is patterned to reducethe visual contrast of the borders or edges of the annular mask 18. FIG.4 shows the contact lens 10 of FIG. 1 with an outer edge 27, which isfeathered to reduce the contrast of the edge 27 as compared to the edge26 of FIG. 1. Other annulus patterns are possible, as long as theoverall visual effect or appearance of the annulus 18 is reduced whenviewed on the eye the wearer.

The feathered edge 27 illustrates one example of a transmissive artifactthat may form part of the annular mask 18 in accordance with theinvention. Such a transmissive artifact represents an area with theannular mask region that is free of the light restricting matter, e.g.,a light-blocking element or a variably transmissive coating, which canform the annular mask 18. Another transmissive artifact is illustratedin FIG. 5, showing the contact lens 10 of FIG. 1 with a plurality ofcurved, arc-like transmissive artifacts 29. Preferably, these artifacts29 are arranged in a geometrical optical configuration, such as shown inFIG. 5, to improve the peripheral vision of the wearer, if needed.However, these artifacts 29 are to be carefully sized and shaped toalleviate undesirable diffraction effects which may be caused by theartifacts. One acceptable artifact shape is illustrated in FIG. 5,whereby the diffraction pattern created by the artifacts 29 is spreadout equally over the retina. The illustrated artifacts 29 have 60° arcs,relative to their radii of curvature, as illustrated in FIG. 5, whichdiffract light to the retina in a pattern much like opposed 60° pieslices. Each respective artifact fills in the diffractive pattern,completing 360° at the retina.

FIG. 6 shows a preferred practice of the invention incorporating abi-powered contact lens 46. The annular mask 48 and the first surface 50of the lens 46 are arranged as described above with reference to FIGS. 1and 1A. The structure of the second surface 52 of the contact lens 46forms two regions that provide two distinct optical corrections. In theregion defined by the pinhole aperture 54, the second surface 52 isoptically configured to correct the wearer's vision for in intermediatedistance, between near and far objects. In addition, the second surface52 in the region outside the annular mask 48 is optically configured tocorrect the wearer's vision for far objects.

As shown in FIG. 6, the light rays 56 which pass through the contactlens 46 enter both the pinhole aperture 54 and the region outside theannular mask 48 during lower lighting conditions, i.e., when the pupil28 of FIG. 2 is dilated. However, all of the light rays 56, whichoriginate from the same object point, effectively focus at the retina,illustratively shown as 58, even with the differing optical correctionsforming surface 52. The light rays 56 which enter the pinhole apertureregion 54 are subjected to greater refracting power at surface 52 yetstill in focus at the retina 58 because of the large depth of focuscreated by the annulus 48. The light rays 56 which pass outside theannular mask 48 are subjected to relatively less refractive power atsurface 52 but also focus at the retina.

Therefore, under average lighting conditions, the pupil 28 of FIG. 2 issomewhat contracted, and the light rays 56 enter only through thepinhole aperture 54, focusing at a point between near and far vision. Indim lighting conditions, the pupil 28 of FIG. 3 is dilated, and thelight rays 56 are focused both intermediately within the pinhole 54 andat far objects outside the mask 48.

The bi-powered nature of the contact lens 46, together with the annularmask 48, enables the wearer to view both far and near objects under thediffering light intensities. The intermediate optical power inside theannular mask 48 and the pinhole aperture 54 provide for the large depthof field.

FIG. 7 shows another contact lens 62 according to the invention andwhich incorporates selective blocking by a mask 64. A pinhole aperture66 and the annular mask diameter 68 are formed by the mask 64 asdescribed above with reference to FIGS. 1, 2 and 2A. The mask 64 is, inaddition, selectively applied to regions 64a outside the annulus outerdiameter 68 to block light energy striking highly irregular portions 70of the iris which may contribute undesirable image effects. The twoillustrated regions 64a are annular portions contiguous with the maskregion within the diameter 68. For example, a damaged iris, or irisregions removed in surgery, would be candidates for selective blockingby a mask region 64a, thereby reducing the negative visual image effectsrelative to those areas 70.

Because the mask 64, including regions such as 64a, can benon-symmetric, the contact lens 62 can be weighted, such as with a prismballast of FIG. 1B, to maintain a particular orientation on the wearer'seye.

It is thus seen that the invention efficiently attains the objects setforth above, among those apparent in the preceding description. Inparticular, the invention provides an annular mask contact lens capableof correcting human vision under differing lighting conditions andviewing distances.

It will be understood that changes may be made in the aboveconstructions without departing from the scope of the invention. Forexample, the arrangement and size of the annular mask 18, as shown inFIGS. 1 and 1A, can be selected for a particular wearer to optimize thevisual correction available in the pinhole contact lens 10. In anotherexample, the contact lens body 12 can be constructed with a yellowappearance, giving the wearer a physiological impression of brighterlighting. In a further example, the contact lens 10, 11, 46, and 62 inFIGS. 1-7, can be constructed with materials, or combinations ofmaterials, forming a soft, gas permeable, hard and semi-hard contactlens. Those skilled in the art will appreciate that the invention canalso aid wearers suffering from other vision deficiencies and disorders.

It is accordingly intended that all matters contained in the abovedescription or shown in the accompanying drawings be interpreted asillustrative rather than in a limiting way.

It is also to be understood that the following claims are intended toclaim all of the specific and generic features of the invention asdescribed herein, and all the statements of the scope of the inventionwhich fall therebetween.

What is claimed is:
 1. A contact lens which comprises:a lens body havinga first surface substantially configured to conform to the eye curvatureof a wearer, said lens body having a second surface opticallyconfigured, in conjunction with said first surface, to correct thevision of the wearer selectively at a focus between and including farand near objects, and said lens body having an annular mask region ofselected optical transmissivity and arranged for(i) forming asubstantially pinhole-like optical aperture which transmits light energythrough the pupil of the wearer, (ii) centering said annular mask regionover the pupil of the wearer, and (iii) permitting increasing lightenergy to pass through said lens body as the pupil of the wearer dilatesduring lower lighting conditions wherein said contact lens is weightedor shaped for centering said aperture at the pupil of the wearer andfurther wherein said contact lens includes means for restricting themotion of said lens body on the eve of the wearer to less thanapproximately one and one-half millimeters.
 2. A contact lens accordingto claim 1 wherein said second surface has an optical configurationoutside said annular mask region which corrects the vision of the wearerselectively at a focus between and including near and far objects, saidsecond surface thereby forming a multi-powered surface.
 3. A contactlens according to claim 1 wherein said second surface has an opticalcorrection, such as an aspheric, convex, concave, or toric correction,for correcting the vision of the wearer.
 4. A contact lens according toclaim 1 wherein said first surface has an optical correction, such as anaspheric or toric correction, for correcting the vision of the wearer.5. A contact lens according to claim 1 wherein said lens body consistsessentially of oxygen permeable material.
 6. A contact lens according toclaim 1 wherein said lens body consists essentially of flexible polymermaterial forming a soft contact lens.
 7. A contact lens according toclaim 1 wherein said lens body has an outer diameter of betweenapproximately seven and eighteen millimeters.
 8. A contact lensaccording to claim 1 wherein said pinhole aperture has a diameter ofbetween approximately one-half and three millimeters.
 9. A contact lensaccording to claim 1 wherein said annular mask region forms an annuluswith a radial width of between approximately one-half and fourmillimeters.
 10. A contact lens according to claim 1 wherein saidannular mask region has a diameter of approximately four and one-halfmillimeters.
 11. A contact lens according to claim 1 comprising meansfor selectively coloring said contact lens.
 12. A contact lens accordingto claim 1 wherein said optical transmissivity is between approximatelyzero and ninety percent in the visible electromagnetic spectrum.
 13. Acontact lens according to claim 1 wherein said annular mask regioncomprises means forming a plurality of light-blocking dots arranged forselectively reducing the transmission of light energy through saidannular mask region by between approximately ten and one hundredpercent.
 14. A contact lens according to claim 1 wherein said annularmask region is selectively translucent.
 15. A contact lens according toclaim 1 wherein said means for restricting the motion includes a prismballast.
 16. A contact lens according to claim 1 wherein said annularmask region has at least one artifact representing an area thattransmits light energy through said lens body with a transmissionsimilar to the transmission of light energy through said aperture.
 17. Acontact lens according to claim 16 wherein said artifact has geometricaloptical structure arranged for improving the peripheral vision of thewearer.
 18. A contact lens according to claim 16 wherein said maskregion has a plurality of arc-shaped artifacts to equally spreaddiffractive light at the retina.
 19. A contact lens according to claim 1wherein said annular mask region is selectively patterned, colored ortinted for reducing the appearance of said annular mask region whenviewed on the eye of the wearer.
 20. A contact lens according to claim 1wherein said annular mask region is selectively colored or tinted formatching, enhancing, or changing the appearance of the iris color of thewearer.
 21. A method for manufacturing a contact lens, comprising thesteps of(A) forming a contact lens body with a first surface configuredto substantially conform to the eye curvature of a wearer and with asecond surface configured, in conjunction with said first surface, tocorrect the vision of the wearer selectively at a focus between andincluding near and far objects, (B) providing on said lens body anannular mask region of selected optical transmissivity, wherein(i) saidannular mask region forms a substantially pinhole-like optical aperturewhich transmits light energy through the pupil of the wearer, (ii) saidannular mask region centers over the pupil of the wearer, and (iii) saidannular mask region permits increasing light energy to pass through thepupil of the wearer during lower lighting conditions as the pupildilates wherein said contact lens is weighted or shaped for centeringsaid aperture at the pupil of the wearer and further wherein saidcontact lens includes means for restricting the motion of said lens bodyon the eve of the wearer to less than approximately one and one-halfmillimeters.
 22. A method according to claim 21 comprising the furtherstep of providing an optical correction outside said annular mask regionwhich selectively corrects the vision of the wearer at a focus betweenand including near and far objects, said second surface thereby forminga multi-powered surface.
 23. A method according to claim 21 comprisingthe further step of providing an optical correction, such as with anaspheric, toric, convex or concave form, on said second surface.
 24. Amethod according to claim 21 comprising the further step of providing anoptical correction, such as with an aspheric, toric or concave form, onsaid first surface.
 25. A method according to claim 21 comprising thefurther step of optimizing the size of the said annular mask region tofit the pupil size of the wearer.
 26. A method according to claim 21comprising the further step of providing additional mask to selectivelyblock portions of the pupil of the wearer that contribute undesirableimage effects.
 27. A method according to claim 21 wherein the step ofproviding an annular mask region of selected optical transmissivityincludes the step of providing light-blocking areas arranged forselectively reducing the transmission of light energy through saidannular mask region by between approximately ten and one hundredpercent.
 28. A method according to claim 21 wherein said mask region thestep of providing an annular mask region of selected opticaltransmissivity includes the step of providing variable transmissioncoatings such that light energy is selectively transmitted through saidannular mask region by between approximately zero and ninety percent.29. A method according to claim 21 wherein the step of forming a lensbody includes the step of forming a lens body having a diameter betweenapproximately seven and eighteen millimeters.
 30. A method according toclaim 21 wherein the step of providing an annular mask region includesthe step of forming an aperture with a diameter of between approximatelyone-half and three millimeters.
 31. A method according to claim 21wherein the step of providing an annular mask region includes the stepof forming an annulus with a radial width of between approximatelyone-half and four millimeters.
 32. A method according to claim 21comprising the further step of selectively coloring or tinted saidcontact lens.
 33. A method according to claim 21 wherein the step ofproviding an annular mask region includes the step of providing alight-restricting element within said lens body.
 34. A method accordingto claim 21 comprising the further step of configuring said firstsurface such that said lens body is restricted for movement on the eyeof the wearer to less than approximately one and one-half millimeter.35. A method according to claim 21 comprising the further step offorming light transmitting artifacts within said annular mask region,said artifacts representing area that transmits light energy throughsaid lens body with a transmission similar to the transmission throughsaid aperture.
 36. A method according to claim 35 comprising the furtherstep of arranging said artifacts in a geometrical optics configurationfor improving the peripheral vision of the wearer.
 37. A methodaccording to claim 35 wherein said step of forming the artifactscomprises the additional step of arranging the artifacts in the annulusto equally spread diffractive light created by said artifacts at thecornea.
 38. A method according to claim 21 comprising the further stepof patterning, coloring, or tinting said annular mask region to reducethe appearance of said annular mask region when viewed on the eye of thewearer.
 39. A non-surgical method for treating visual aberrations, saidmethod comprising the steps of(A) fitting at least one eye of a wearerwith a first contact lens configured to correct the vision of a wearerat a focus between and including near and far objects, (B) providing onsaid contact lens an annular mask region of selected opticaltransmissivity, wherein(i) said annular mask region forms asubstantially pinhole-like optical aperture for the pupil of the wearer,(ii) said annular mask region centers over the pupil of the wearer, and(iii) said annular mask region permits increasing light energy to passthrough the pupil of the wearer during lower lighting conditions as thepupil dilates wherein said contact lens is weighted or shaped forcentering said aperture at the pupil of the wearer and further whereinsaid contact lens includes means for restricting the motion of said lensbody on the eye of the wearer to less than approximately one andone-half millimeters.
 40. A method according to claim 39, comprising thefurther step of fitting only one eye of the wearer with said firstcontact lens and fitting the other eye with a contact lens of selectedpower that is substantially free of an annular mask region.